The Arctic continues to undergo dramatic change due to atmospheric and ocean warming, and the region “is no longer returning to the extensively frozen region of recent past decades,” according to the 2018 Arctic Report Card issued by the National Oceanic and Atmospheric Administration (NOAA) at AGU’s Fall Meeting 2018 on Tuesday.

A Teshekpuk caribou in the National Petroleum Reserve, Alaska. The report card states that the abundance of migratory herds of caribou and wild reindeer in circum-Arctic tundra areas has declined 56% in the past 2 decades. Credit: Bob Wick, BLM

“The Arctic is experiencing the most unprecedented transition in human history,” said Emily Osborne, lead author of the report and manager of NOAA’s Arctic Research Program. “In 2018, the effects of persistent Arctic warming continue to mount. Warming air and ocean temperatures continue to drive broad, long-term change across the region, pushing the Arctic into uncharted territory.”

The report states that “new and rapidly emerging threats are taking form and highlighting the level of uncertainty in the breadth of environmental change that is to come.”

Programs to conduct long-term monitoring “are critical to understanding baseline conditions and the magnitude and frequency of the changes that are being delivered to the Arctic,” the report continues. “Such understanding is central to the livelihood of communities that call the Arctic home as well as the rest of the globe which is already experiencing the changes and implications of a warming and melting Arctic.”

Here are some of the main findings in the report:

In 2018, surface air temperatures in the Arctic continued to warm at more than twice the rate relative to the rest of the globe. The year 2018 was the second warmest year on record in the Arctic since 1900; its temperature of 1.7°C above the long-term average of 1981–2010 is second only to 2016. Arctic air temperatures for the past 5 years—2014–2018—have exceeded all previous records since 1900.

Older sea ice declined by 95% between March 1985 and March 2018.Arctic sea ice cover, which reached a winter maximum value extent of 14.48 million square kilometers on 17 March 2018, was the second lowest maximum extent in the 39-year record, following 2017. The 2018 extent was 7.3% below the 1981–2010 average, and the past 4 years—2015–2018—are the four lowest maximums in the satellite record.

Older sea ice, which tends to be thicker and more resilient to changes in atmospheric and oceanic heat content compared to younger and thinner ice, declined by 95% between March 1985 and March 2018. In 1985, ice four or more years old comprised 16% of the Arctic ice pack and 2.54 million square kilometers; in March 2018 the older ice comprised 0.9% of the ice pack and 0.13 million square kilometers.

For nearly all of the 2017–2018 Bering Sea ice season, the ice extent was at a record low. With reduced sea ice coverage and early breakup of ice, the effect on ocean primary productivity was profound, and productivity levels in the Bering Sea region sometimes were 500% higher than normal levels.

The warming Arctic Ocean may be experiencing an increase in the extent and magnitude of toxic harmful algal blooms, which poses threats to human and ecosystem health.

Increased atmospheric warmth in the Arctic “results in a sluggish and unusually wavy jet-stream that coincided with abnormal weather events in both the Arctic and mid-latitudes.” Extreme weather events coincident with deep waves in the jet stream include the heat wave at the North Pole in autumn 2017, severe winter storms in the eastern United States in 2018, and an extreme cold outbreak in Europe in March 2018.

The report card calls marine microplastics an “emerging threat” in the Arctic.Although some impacts of climate change on extreme weather are clear—more severe heat waves, more frequent heavy-precipitation events, and more intense droughts—the understanding of other less direct influences is less clear. “The role of a rapidly warming and melting Arctic is one of these factors that challenges present computer modeling capabilities and understanding of atmospheric dynamics,” the report states. “Exactly how the northern meltdown will ‘play ball’ with other changes and natural fluctuations in the system presents many questions that will keep scientists busy for years to come, but it’s becoming ice-crystal-clear that change in the far north will increasingly affect us all.”

The report card calls marine microplastics an “emerging threat” in the Arctic, and it notes that a recent global survey shows that the Arctic Ocean has higher concentrations of microplastics than any other ocean basin in the world.

The abundance of migratory herds of caribou and wild reindeer in circum-Arctic tundra areas has declined 56% in the past 2 decades, dropping from 4.7 million to 2.1 million animals. Five herds in the Alaska-Canada region have declined by more than 90% and show no sign of recovery. This decline threatens the food security and culture of indigenous people, according to the report. Although it is normal for herd numbers to vary over decades, some herds currently have all-time low populations since reliable record keeping began, the report states.

The report card, which also looks at trends in terrestrial snow cover, the Greenland ice sheet, and tundra greenness, among other environmental changes, is a peer-reviewed report that was compiled from research by 81 scientists working for governments and academia in 12 countries.

Briefing President Trump?

NOAA acting director Tim Gallaudet said at the briefing that “the report card summarizes some very significant changes.” However, despite concerns about the Arctic, Gallaudet acknowledged in response to a reporter’s question that neither he nor any other senior NOAA official has briefed President Trump about climate change or the changes in the Arctic since Trump took office on 20 January 2017.

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